Acetals useful for the preparation of polysaccharide derivatives

ABSTRACT

Polysaccharide aldehydes having the formula Sacch--O--CH 2  --CH═CH--CHO, Saach--O--CH 2  --C.tbd.C--CHO, ##STR1## starch, cellulose, and gum aldehydes, are useful for imparting wet, dry, or temporary wet strength to paper. They are prepared by a non-oxidative method which involves reacting the polysaccharide base, in the presence of alkali, with a derivatizing acetal reagent having the general structure ##STR2## and then hydrolyzing the acetal by adjusting the pH to less than 7, preferably 2-4. In the formulas, n is 1-3; R 11  and R 12  are independently an alkyl, aryl, aralkyl, or alkaryl group when n is 1, R 11  or R 12  is one of the groups when n is 2, or R 11  and R 12  are not present when n is 3; R 13  is an alkyl group, optionally containing an ether linkage, or an aralkyl group; R 14  and R 15  are individually a hydrogen or a methyl group; R 16 , R 17 , and R 18  are individually an alkyl group; Y -  is an anion; Z is an organic group capable of reacting with the polysaccharide base to form an ether derivative and selected from the group consisting of an epoxide, ethylenically unsaturated group, halohydrin, and halogen; R 19 , if present, is a divalent organic group containing no reactive substiuents; and A and A&#39; are lower alkyls or together form at least a 5-membered cyclic acetal.

This application is a division of Ser. No. 037,282, filed Apr. 10, 1987,now U.S. Pat. No. 4,804,769 issued Feb. 14, 1989; which is a division ofSer. No. 829,675 filed Feb. 14, 1986, now U.S. Pat. No. 4,703,116 issuedOct. 27, 1987; which is a continuation-in-part of Ser. No. 758,634 filedJuly 24, 1985, now U.S. Pat. No. 4,675,394 issued June 23, 1987; whichis a continuation-in-part of Ser. No. 641, 820 filed Aug. 17, 1984, nowabandoned.

BACKGROUND OF THE INVENTION

The present invention relates to polysaccharide derivatives containingaldehyde groups and to the acetal derivatives used in the preparationthereof. It also relates to a non-oxidative process for introducingaldehyde groups into polysaccharides. It further relates to the use ofthe cationic aldehyde-containing derivatives as paper additives.

As used herein, the term "paper" includes sheet-like masses and moldedproducts made from fibrous cellulosic materials which may be derivedfrom natural sources as well as from synthetics such as polyamides,polyesters, and polyacrylic resins, and from material fibers such asasbestos and glass. In addition, papers, made from combinations ofcellulosic and synthetic materials are applicable herein. Paperboard isalso included within the broad term "paper".

Oxidative and non-oxidative methods have been used to introduce aldehydegroups into polysaccharides such as starches, gums, and celluloses. Theoxidative methods used have included treatment with periodic acid,periodates, or alkali metal ferrates. See U.S. Pat. No. 3,086,969(issued April 23, 1963 to J. E. Slager) which discloses an improvedprocess for the preparation of a dialdehyde polysaccharide (e.g.,starch) using periodic acid; U.S. Pat. No. 3,062,652 (issued Nov. 6,1962 to R. A. Jeffreys et al.) which discloses the preparation ofdialdehyde gums (e.g., gum acacia, pectin, and guar) using periodate orperiodic acid; and U.S. Pat. No. 3,632,802 (issued Jan. 4, 1972 to J. N.BeMiller et al.) which discloses a method for oxidizing a carbohydrate(e.g., starch or cellulose with an alkali metal ferrate.

In the above methods the aldehyde groups are formed by the oxidation ofthe hydroxyl groups on the ring and/or side chain. Treatment withperiodic acid or periodate selectively oxidizes the adjacent secondaryhydroxyl groups on the ring carbon atoms (e.g., the 2,3-glycolstructures), cleaves the ring, and results in a "so-called" dialdehydederivative which is principally a hydrated hemialdal and intra- andintermolecular hemiacetals. Treatment of carbohydrates with alkali metalferrates selectively oxidizes the primary alcohol group on the sidechains without ring cleavage or oxidation of the ring hydroxyls.

The disadvantages of the oxidative method include degradation to lowermolecular weight products and the formation of carboxyl groups due tofurther oxidation of the aldehyde groups. U.S. Pat. No. 3,553,193(issued Jan. 5, 1973 to D. H. LeRoy et al.) describes a method foroxidizing starch using an alkali metal bromite or hypobromite undercarefully controlled conditions. The resulting dialdehyde is reported tohave a substantially greater proportion of carbonyl groups (i.e.,aldehyde groups) than carboxyl groups. It also discloses a method forselectively oxidizing the side chains of starch derivatives (e.g., analkoxylated starch such as dihydroxypropyl starch) under the sameprocess conditions whereby the underivatized starch hydroxy groups onthe rings are substantially non-oxidized.

The presence of carboxylic groups in aldehyde starches has severaldisadvantages in addition to the obvious reduction in the degree ofaldehyde substitution. These include the introduction of hydrophilicproperties due to the carboxyl groups, an upset in the cationic/anionicratio when a cationic starch base is used (as in most papermaking wetend uses), and the possible formation of salts (in the abovepaper-making end use) which could give rise to ionic crosslinking.

The non-oxidative methods typically involve the reaction of thepolysaccharide with an aldehyde-containing reagent. See U.S. Pat. No.3,519,618 (issued July 7, 1970 to S. M. Parmerter) and U.S. Pat. No.3,740,391 (issued June 19, 1973 to L. L. Williams et al.) which coverstarch derivatives and U.S. Pat. No. 2,803,558 (issued Aug. 20, 1957 toG. D. Fronmuller) which covers a gum derivative. The starch derivativeof Panmerter is prepared by reaction with an unsaturated aldehyde (e.g.acrolein) and has the structure Starch--O--CH(R¹)--CH(R²)--CHO where R¹and R² are hydrogen, lower alkyls or halogen. The starch derivative ofWilliams is prepared by reaction with acrylamide followed by reactionwith glyoxal and has the structure ##STR3## The gum derivative ofFronmuller is prepared by treating the dry gum (e.g., locust bean orguar gum) with peracetic acid to reduce the viscosity, neutralizing, andthen reacting with glyoxal. Water-soluble cellulose ethers (e.g.,hydroxyethylcellulose) have also been reacted with glyoxal orureaformaldehyde to give aldehyde-containing derivatives.

One of the disadvantages of introducing the aldehyde groups directlyusing an aldehyde-containing reagent is the possibility of thederivative crosslinking prior to use. This is a particular disadvantagewhen the products are being used to impart temporary wet strength topaper via a crosslinking reaction with the cellulose fibers. TheWilliams patent (cited above) alludes to this problem when it notes thatsolutions of the glyoxalated polymers "are stable for at least a weekwhen diluted to 10% solids by weight and adjusted to pH 3" (see Col. 3,lines 60-63). The Parmerter patent notes that the starch aldehyde is "asubstantially non-crosslinked granular starch derivative" and discussesthe importance of the non-crosslinked character (see Col. 2, lines40-45).

Therefore there is a need for aldehyde-containing polysaccharidederivatives and an improved non-oxidative method for their preparationwhich does not crosslink the derivative.

SUMMARY OF THE INVENTION

The present invention discloses polysaccharide aldehyde derivativeswhich have the formula ##STR4## as well as polysaccharide acetals whichhave the formula ##STR5## The preparation of the above aldehyde andacetals is described in Ser. No. 641,820 filed Aug. 17, 1984, thedisclosure of which is incorporated herein by reference.

The present invention provides the following novel aldehyde-containingpolysaccharide derivatives, as well as the correspondingacetal-containing polysaccharide derivatives.

1. An aldehyde-containing polysaccharide derivative which has theformula Sacch--O--CH₂ --CH═CH--CHO, as well as an acetal-containingpolysaccharide derivative which has the formula ##STR6##

2. An aldehyde-containing polysaccharide derivative which has theformula Sacch--O--CH₂ --C.tbd.C--CHO and an acetal-containingpolysaccharide derivative which has the formula ##STR7##

3. An aldehyde-containing polysaccharide derivative which has theformula ##STR8## and an acetal-containing polysaccharide derivativewhich has the formula ##STR9## where n=1 when both R¹¹ and R¹² arepresent, n=2 when only R¹¹ or R¹² are present, or n=3 when neither R¹¹or R¹² are present.

4. An aldehyde-containing polysaccharide derivative which has theformula ##STR10## and an acetal-containing polysaccharide derivativewhich has the formula ##STR11##

5. An aldehyde-containing polysaccharide derivative which has theformula ##STR12## and an acetal-containing polysaccharide derivativewhich has the formula ##STR13##

6. An aldehyde-containing polysaccharide derivative which has theformula ##STR14## polysaccharide derivative which has the formula##STR15##

7. An aldehyde-containing polysaccharide derivative which has theformula ##STR16## and an acetal-containing polysaccharide derivativewhich has the formula ##STR17##

8. An aldehyde-containing polysaccharide derivative which has theformula ##STR18## and an acetal-containing polysaccharide which has theformula ##STR19##

It also provides a polysaccharide aldehyde having the formulaSacch--O--R¹⁹ --CHO prepared by hydrolyzing, at a pH of about 6 or less,a polysaccharide acetal having the formula ##STR20## which is preparedby reacting the polysaccharide, at a pH of about 9 or above, with anacetal reagent which does not substantially crosslink or oxidize thepolysaccharide during the reaction. The reagent is described hereafter.

In the above formulas Sacch--O--represents a polysaccharide molecule(wherein the hydrogen of a hydroyxl group of a saccharide unit has beenreplaced as shown); R is (CH₂)_(n) or a divalent aromatic group and n iszero or greater; R⁹ is (CH₂)_(n) or a divalent aromatic group and n iszero or greater, with the proviso that n is 1 or more when thepolysaccharide molecule is a starch molecule; R¹, R⁶ and R⁷ arehydrogen, an alkyl (preferably methyl), aryl, aralkyl, or alkaryl group;R², R⁵ and R⁸ are (CH₂)_(m) with m being 1-6 (preferably 1-2); R³ and R⁴are hydrogen or a lower alkyl, preferably methyl; R¹¹ and R¹² areindependently an alkyl, aryl, aralkyl or alkaryl group, preferably alower alkyl group, most preferably methyl; R¹³ is an alkyl group,optionally containing an ether linkage, or an, aralkyl; R¹⁴ and R¹⁵ areindividually hydrogen or a methyl group; R¹⁶, R¹⁷ and R¹⁸ are analkylene, preferably a lower alkylene most preferably methylene; R¹⁹ isdivalent organic group containing no starch-reactive substituents; A,A', A", and A"' are independently a lower alkyl or A and A' togetherform at least a 5-membered cyclic acetal; and Y is an anion such as ahalide, sulfate, or nitrate. The polysaccharide molecule may be modifiedby the introduction of cationic, anionic, nonionic, amphoteric, and/orzwitterionic substituent groups. As used herein, the terms "cationic"and "anionic" are intended to cover cationogenic and anionogenic groupsand the term "reactive substituents" refers to substituents which reactwith polysaccharide to form a covalent bond.

The aldehydes are prepared by hydrolyzing the corresponding acetal at apH of less than 7, preferably 5 or less, most preferably 2.0-4.0. Theacetals are prepared by reacting the polysaccharide with an acetalreagent having the general structure ##STR21## where Z is an organicgroup capable of reacting with the saccharide molecule to form an etherderivative and selected from the group consisting of an epoxide, ahalohydrin, an ethylenically unsaturated group, and a halogen and R¹⁹,if present, is a divalent organic group containing no reactivesubstituents.

Typical reagents for preparing the acetal-containing derivatives shownin (1) have the formula ##STR22## and for preparing theacetal-containing derivatives shown in (2) have the formula ##STR23##

The present invention also provides novel acetal-containing reagents(some of which are cyclic acetals) for preparing the acetal-containingderivatives shown in (3), (4), and (5). The reagents have the followingformulas: ##STR24## R¹¹, R¹², R¹³, A and A' are as defined previously Zis a halogen, preferably chlorine or bromine or an epoxide group##STR25##

The acetal-containing reagents shown in (a) can be prepared by theconventional reaction of a dihalo butene with the appropriate amine,typically a tertiary amine, in an organic solent. The reaction isdescribed in articles by R. S. Shelton et al. in J. Am. Chem. Soc. 68,753, 755, 757 (1946), by P. Walden in Z. Elektrochem. 27, 36 (1921), andby C. R. McCrosky et al. in J. Am. Chem. Soc. 62, 2031 (1940).

The acetal-containing reagents, shown in (b) to (c) can be prepared bytwo methods.

The first method involves converting an alcohol-containing aldehyde(e.g., 3-hydroxy-2,2-dimethylpropionaldehyde to the acetal by treatmentwith an excess of an anhydrous alcohol (e.g., methanol) in the presenceof a trace amount of an acid. The acetal is then reacted with anepihalohydrin (e.g., epichlorohydrin) under conditions that will notaffect the acetal group (i.e., under alkaline conditions). Theepihalohydrin addition is described in an article by R. Pozniak and J.Chlebicki entitled "Synthesis of Higher N-(2-Hydroxy-3-alkoxypropyl)ethanolamines and N-(2-Hydroxy-3-alkoxypropyl)diethanolamines", PolishJ. Chem. 52, p. 1283 (1978).

The second method involves the addition of two moles of a diol (e.g.,ethylene glycol) to 1 mole of an unsaturated aldehyde (e.g.,croton-aldehyde or acrolein) to give an alcohol-containing dioxolanewhich is then reacted with an epihalohydrin as discussed above. Theaddition of diols to unsaturated aldehydes is discussed in an article byA. Piasecki entitled "Acetals and Ethers XIII. Reaction Products of2-Butenal with Ethylene Glycol", Tetrahedron 40, p. 4893 (1984).

The addition is reported to produce the acetal and ethoxy ether in onestep, as shown below. ##STR26##

By controlling the reaction conditions (room temperature or slightlyabove) and choosing a diol that is water-insoluble (e.g.,2,2-dimethyl-1,3-propanediol), the reaction will stop after addition toonly the aldehyde. The reaction of acrolein with a diol to form anacetal is described in U.S. Pat. No. 4,108,869 (issued Aug. 22, 1978 toH. B. Copelin). Addition of a halohydrin (e.g.,3-chloro-1,2-propanediol) to the double bond can be accomplished in a2nd step if catalytic amounts of acid (e.g., p-toluenesulfonic acid) arepresent and the reaction is carried out with heating in a solvent (e.g.,cyclohexane or methyl ethyl ketone). The equations below show the 2-stepreaction. ##STR27##

The present invention further provides novel acetal-containing reagentsprepared by the ring opening of furans under very mild conditions. Thereagents used to prepare the acetals shown in (6) and (7) have theformulas: ##STR28## They are prepared from furan derivatives which canbe reacted with a reagent capable of introducing a starch reactive group(e.g., an epoxide, halohydrin, or ethylenically unsaturated group)followed by a ring opening reaction to form the acetal. The reactionsproceed as follows: ##STR29##

The reagents used to prepare the acetal shown in (8) have the structure##STR30## They are prepared by directly ring opening furan a containinga starch reactive group. The reaction proceeds as follows: ##STR31##

The ring opening reaction using a simple alcohol (e.g., CH₃ OH) or adiol (e.g., ethylene glycol) is carried out under mild conditions usingthe procedure described by S. M. Makin and N. I. Telegina in J. Gen.Chem. USSR 32, 1082-87 (1962) and in U.S. Pat. No. 3,240,818 issuedMarch 16, 1966 to D. M. Burness. When the diol is used, a cyclic acetalwill result. The use of a mixture of alcohols will result in a mixedacetal and the A groups will be different.

The aldehyde and acetal derivatives are useful in conventionalapplications where water-soluble or water-swellable polysaccharidederivatives are useful, for example, as coatings, adhesives, and paperand textile additives. Most of the aldehyde-containing derivatives areuseful as temporary wet strength additives, for example intissue/toweling paper stocks, and as wet and dry strength additives forall paper types including liner board. When the aldehydes are preparedfrom cyclic acetals, five-membered acetal rings are preferred since suchrings are easier to hydrolyze than six-membered rings. The more severeconditions required to hydrolyze the six-membered rings lead todegradation of the polysaccharide, and this impairs their efficiency aspaper additives.

The derivatives typically contain cationic and cationogenic groups inaddition to the aldehyde groups. These include diethylaminoethyl ethergroups introduced by reaction with 2-diethylaminochloride hydrochlorideor 3-(trimethylammonium chloride)-2-hydroxypropyl ether groupsintroduced by reaction with 3-chloro-2-hydroxypropyl trimethylammoniumchloride. The aldehyde-containing derivatives containing quaternaryammonium groups, i.e., ##STR32## and the aldehyde having the structure##STR33## where R¹³ is a difunctional aryl group and the ⁻⁻ CHO group isattached directly to the aromatic ring (e.g., Reagent S in Example XI),are not useful as wet paper strength additives. As used herein, the termaromatic ring is intended to include not only conjugated hydrocarbonsbut also conjugated heterocylic systems.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

When the polysaccharide is starch, applicable starch bases which may beused herein may be derived from any plant source including corn, potato,sweet potato, wheat, rice, sago, tapioca, waxy maize, sorghum, highamylose corn, or the like. Starch flours may also be used as a starchsource. Also included are the conversion products derived from any ofthe former bases including for example, dextrins prepared by thehydrolytic action of acid and/or heat; oxidized starches prepared bytreatment with oxidants such as sodium hypochlorite; fluidity orthin-boiling starches prepared by enzyme conversion or mild acidhydrolysis; and derivatized and crosslinked starches. The starch basemay be a granular starch or a gelatinized starch, i.e. non-granularstarch.

When the polysaccharide is gum, applicable bases which may be usedherein are polygalactomannans, which are heteropolysacchrides composedprincipally of long chains of 1→4 βD-mannopyranosyl units to whichsingle unit side chains of α-D-galactopyranosyl units are joined by 1→6linkages and hereafter referred to as "gums". Also included are degradedgum products resulting from the hydrolytic action of acid, heat, shear,and/or enzyme; oxidized gums; and derivatized gums. The preferred gumsinclude gum arabic, as well as guar gum and locust bean gum because oftheir commercial availability.

When the polysaccharide is cellulose, applicable bases useful hereininclude cellulose and cellulose derivatives, especially water-solublecellulose ethers such as alkyl and hydroxyalkylcelluloses, specificallymethylcellulose, hydroxypropylmethyl cellulose,hydroxybutylmethylcellulose, hydroxyethylmethylcellulose, andethylhydroxyethylcellulose.

Methods for preparing the modified polysaccharide bases are well knownto those skilled in the art and discussed in the literature. See, forexample, R. L. Whistler, Methods in Carbohydrate Chemistry, Vol. IV,1964, pp. 279-311; R. L. Whistler et al., Starch-Chemistry andTechnology, Vol. II, 1967, pp. 293-430; R. L. Davidson and N. Sittig,Water-Soluble Resins, 2nd Ed., 1968, Chapter 2; and R. L. Davison,Handbook of Water-Soluble Gums and Resins, 1980, Chapters 3, 4, 12 and13 directed to cellulose derivatives, Chapters 6 and 14 directed togums, and Chapter 22 directed to starch.

The starch reactions with the derivatizing reagents that introduce theacetal groups are carried out using the general procedure described inU.S. Pat. No. 3,880,832 issued April 29, 1975 to M. M. Tessler. Granularreactions are typically carried out in water at 20°-50° C., preferablyabout 40°-45° C. Non-granular starch reactions may be carried out athigher temperatures (e.g., up to 100° C.). The reaction mixture ispreferably agitated. Reaction time may vary from about 0.5-40 hours,preferably 8-24 hours, for aqueous reactions or from about 1-8 hours forreactions carried out in a substantially dry reaction medium. It willdepend on such factors as the amount of reagent employed, thetemperature, the scale of the reaction, and the degree of substitutiondesired. The pH is maintained at about 10-13, preferably 11-12, duringthe reagent addition and during the entire reaction using a base such assodium, potassium, or calcium hydroxide. Sodium sulfate is typicallyadded to the reaction mixture to reduce swelling of the granular starch;it is not used when calcium hydroxide is the base. Potassium or sodiumiodide is a good catalyst for reacting the chloroacetylated aminederivatives, but it is not necessary for a satisfactory reaction withthe starch. After completion of the reaction, the excess alkali isneutralized and the pH is adjusted to about 7-8 using any conventionalacid prior to recovery of the starch. If the final pH of the starchderivative is less than about 5-6, the derivatives may crosslink withtime and disperse poorly or not at all.

The gum reactions with the acetal reagents are carried out in atwo-phase reaction system comprising an aqueous solution of awater-miscible solvent and the water-soluble reagent in contact with thesolid gum. The water content may vary from 10 to 60% by weight dependingupon the water-miscible solvent selected. If too such water is presentin the reaction system, the gum may swell or enter into solution therebycomplicating recovery and purification of the derivative. Thewater-miscible solvent is added in the amount sufficient for thepreparation of a slurry which can be agitated and pumped. The weightratio of water-miscible solvent to gum may vary from 1:1 to 10:1,preferably from 1.5:1 to 5:1. Suitable water-miscible solvents includealkanols, glycols, cyclic and acylic alkyl ethers, alkanones,dialkylformamide and mixtures thereof. Typical solvents includeaethanol, ethanol, isopropanol, secondary pentanol, ethylene glycol,acetone, methyethylketone, diethylketone, tetrahydrofuran, dioxane, anddimethylformamide. The reaction times and temperatures used for theaqueous reactions are suitable for the solvent reaction.

The cellulose reactions with the acetal reagents are convenientlycarried out using the procedure of U.S. Pat. No. 4,129,722 (issued Dec.12, 1978 to C. P. Iovine et al.). The cellulose or cellulose derivativeis suspended in an organic solvent and a water solution of thederivatizing reagent is added thereto. Derivatization in the resultanttwo-phase mixture is ordinarily carried out with agitation attemperatures of 30° to 85° C., adding alkali if necessary to effectreaction. At least one of the initial phases (i.e., the suspendedcellulose or cellulose derivative or the aqueous reagent solution)contains a suitable surfactant. It is important that the organic solventused in the initial cellulose phase be immiscible with the aqueousderivatizing reagent phase, that it not dissolve the cellulosederivative as it is formed, that it have a boiling point at or above thetemperature of the derivatizing reaction, that it be insensitive toalkali and not participate in the derivatization reaction.

The two phase procedure may also be used to prepare starch and gumderivatives as well as cellulose derivatives. It may also be used toprepare derivatives containing substituents derived from differentreagents without isolating the substitution product from each reagent.This multiple substitution may be accomplished by the addition ofseveral different reagents to the substrate-surfactant alkali mixture atthe same time or sequentially.

After completion of the acetal reaction the solid polysaccharide acetalsmay be separated, if desired, from the reaction mixture bycentrifugation or filtration. Preferably, the derivative is purified bywashing with water in the case of the starch derivatives, with theaqueous solution of water-miscible solvent in the case of the gumderivatives or with the solvent in the case of the cellulosederivatives. Further washing with a more anhydrous form of the samesolvent may be desirable for the gum derivatives. The derivatives arethen dried using conventional methods, as in a vacuum drum, flash, belt,or spray drier.

The conversion of the polysaccharide acetals to the aldehydes is carriedout under acidic conditions, typically at a pH of 6 or less, preferably5 or less, most preferably at about 2-3. It may be carried out directlywithout isolation of the acetal or the acetal may be isolated as aboveand resuspended in water prior to conversion. If desired, thederivatives may be recovered as described above.

In addition to preparing the above acetal or aldehydes, modifiedderivatives may be prepared which contain other substitutent groups,hydroxyalkyl groups (e.g., hydroxypropyl ether groups), carboxyalkylether groups (e.g., carboxymethyl), ester groups (e.g., acetate groups),tertiary amino groups (e.g., diethylaminoethyl ether groups), andquaternary amine groups, (e.g. 3-(trimethylammoniumchloride)-2-hydroxypropyl groups or 4-(trimethylammoniumchloride)-2-butenyl groups), introduced prior to or subsequent toreaction with the acetal derivatizing reagent or introducedsimultaneously by reaction with the acetal reagent and otherderivatizing reagent. The practitioner will recognize that reactionswith reagents introducing labile ester groups should be carried outafter the other derivatizations to avoid ester hydrolysis under thealkaline conditions used to prepare other derivatives.

The aldehyde derivatives used as paper additives preferably containcationic groups, such as the quaternary ammonium and tertiary aminegroup discussed above, amphoteric, and/or zwitterionic groups. Thesederivatives are dispersed in water before use. The granular starchderivatives are cooked to provide the dispersed derivative.

The starch may be cooked prior to derivatization to form the acetal,subsequent to derivatization, after conversion to the aldehyde, or mostconveniently during conversion of the acetal to the aldehyde. Cooking atpH 6 or less simultaneously converts the acetal to aldehyde andsolubilizes and disperses the starch aldehyde. Any conventional cookingprocedure ray be used, such as cooking a slurry containing thewater-soluble or water-swellable derivative in a boiling water bath forabout 20 minutes, blowing in steam to heat the slurry to about 93° C.(200° F.), or jet cooking. If a water-dispersible or water-solublestarch base is used for the preparation of the acetal, it will not benecessary to cook the acetal during the acid hydrolysis.

The aldehyde derivatives described herein may be used as beateradditives, although their addition to the pulp may occur at any point inthe paper-making process prior to the ultimate conversion of the wetpulp into a dry web or sheet. Thus, for example, they may be added tothe pulp while the latter is in the hydropulper, beater, various stockchests, or headbox. The derivatives may also be sprayed onto the wetweb. If the derivative is trapped in the wet fibers after spraying, itmay not be necessary to use cationic aldehyde derivatives but they arepreferred.

The aldehydes herein may be effectively used for addition to pulpprepared from any type of cellulosic fibers, synthetic fibers, orcombinations thereof. Among the cellulosic materials which may be usedare bleached and unbleached sulfate (kraft), bleached and unbleachedsulfite, bleached and unbleached soda, neutral sulfite, semi-chemicalchemiground wood, ground wood or any combination of these fibers. Fibersof the viscous rayon or regenerated cellulose type may also be used ifdesired.

Any desired inert mineral fillers may be added to the pulp which is tobe modified with the aldehydes herein. Such materials include clay,titanium dioxide, talc, calcium carbonate, calcium sulfate anddiatomaceous earths. Rosin or synthetic internal size may also bepresent if desired.

The proportion of the aldehyde to be incorporated into the paper pulpmay vary in accordance with the particular pulp involved and theproperties desired (e.9., wet strength, temporary wet strength, or drystrength). In general, it is preferred to use about 0.1-10% preferablyabout 0.25-5% of the derivative, based on the dry weight of the pulp.Within this preferred range the precise amount which is used will dependupon the type of pulp being used, the specific operating conditions, theparticular end use for which the paper is intended, and the particularproperty to be imparted. The use of amounts greater than 5%, based onthe dry weight of the pulp, is not precluded, but is ordinarilyunnecessary in order to achieve the desired results.

It can be appreciated by the practitioner that a large number ofvariations may be effected in selecting the acetal derivatizingreagents, reacting them with the bases, converting them to thealdehydes, and utilizing the aldehyde derivatives as wet end additivesfor paper in accordance with the procedure described above withoutmaterially departing from the scope and spirit of the invention. Suchvariations will be evident to those skilled in the art and are to beincluded within the scope of the invention.

In the examples which follow, all parts and percentages are given byweight and all temperatures are in degrees Celsius unless otherwisenoted. Reagent percentages are based on dry polysaccharide.

The nitrogen content of the cationic bases and resulting acetals wasmeasured by the Kjeldahl method and are based on dry polysaccharide.

The presence of aldehyde groups was determined qualitatively by theviscosity increase of a cooked slurry and/or gel formation andquantitatively by titration. The quantitative test is carried out byslurrying 5.0 g. of the polysaccharide acetal in sufficient distilledwater to give 500 g. The pH is adjusted to 2.5 with hydrochloric acid.The polysaccharide is dispersed by cooking in a boiling water bath for20 minutes. The dispersed polysaccharide is cooled and the solidsdetermined. A 100 g. portion of the dispersed polysaccharide is weighedout, titrated with 0.1 NaOH to the first end point (inflection point isbetween pH 4.0 and 5) and the ml. of NaOH required is recorded (T₁). Anaqueous solution (50 ml.) of hydroxylamine hydrochloride (prepared bydissolving 34.75 g. in 1000 ml. volumetric flask and diluting to themark) is added to a 100 g. portion of the dispersed polysaccharide,heated at reflux for 60 minutes, and titrated with 0.1 N NaOH to pH 4.5.The ml. of NaOH required to reach the inflection point (pH 3.0-3.5) isrecorded (T₂). ##EQU1## *polysaccharide weight=100 g. x % solids ofdispersed polysaccharide Best results are obtained using an automatictitrator. A blank using the base polysaccharide (i.e., unmodified by theintroduction of acetal groups) ray also be run.

In the paper tests, the tensile strengths are reported as breakinglength (m.). The breaking length is the calculated limiting length of astrip of uniform width, beyond which, if such as strip were suspended byone end, it would break of its own weight. The breaking length (air dry)in meters (m.) is calculated using the formula B.L.=102,000 T/R=3,658T'/R', where T is tensile strength in kN./m., T' is tensile strength in1b./in., R is grammage (air dry) in g./m.², and R' is weight per unitarea (air dry in 1b./1000 ft.²). Paper specimens are selected inaccordance with TAPPI T 400 sampling procedure. Those evaluated for wetstrength and temporary wet strength were saturated with distilled waterby immersion and/or soaking until the paper sample was thoroughlywetted. The strength was evaluated in accordance with TAPPI T 494 om-82.The measurements were carried out using a constant rate of elongationapparatus, i.e., a Finch wet strength device, which is described inTAPPI Procedure T 456 om-82 (1982). The dry strength was evaluated inaccordance with TAPPI T 494 om-81.

EXAMPLE I

This example describes the preparation of known cationic starch acetalsby several methods using various starch bases. The reagents used forpreparing the starch acetals have the general formula ##STR34## where R¹is H or --CH₃, R² is --CH₂ --, A and A' are --CH₃ or --C₂ H₅, and X isCl or Br. They are prepared by reacting a haloacetyl halide withaminoacetaldehyde diethyl acetal or methylaminoacetaldehyde dimethylacetal as described below.

Acetal Reagent Preparation

Reagent A --N--(2,2-Dimethoxyethyl)-N-methyl-2-chloracetamide, which hasthe formula ##STR35## is prepared by adding chloroacetyl chloride (29.05g.) dropwise to a stirred mixture of methylaminoacetaldehyde dimethylacetal (33.5 g.) in toluene (170 ml.) and 20% aqueous sodium hydroxide(52.9 g.). The reaction was cooled by immersion in an ice/brine bath andthe addition rate was adjusted to maintain the reaction temperature at0°-5° C. The total addition took 10 mins. at which time the cooling bathwas removed. Agitation was continued for an additional 10 mins. and thephases were then separated. Excess toluene was removed from the upperorganic phase by distillation at the aspirator to give Reagent A as abrown liquid.

Reagent B--N-(2,2-Diethoxyethyl)chloroacetamide, which has the formula##STR36## was prepared as above except that aminoacetaldehyde diethylacetal (37.4 g.) was substituted for the aethylaminoacetaldehydedimethyl acetal. The product was isolated as a yellow waxy solid.

Reagent C --N--(2,2-Dimethoxyethyl)-N-methyl-2-bromoacetamide, which hasthe formula ##STR37## was prepared in the same way as Reagent A exceptthat bromoacetyl chloride (40.4 g.) was substituted for the chloroacetylchloride. The product was isolated as a brown liquid.

Starch Reactions Part A. Consecutive Reactions Using Cationic ReagentFollowed by Acetal Reagent

(1) A waxy maize starch (250 g.) was slurried in 375 ml. of water. Tothe slurry was added 2.3% calcium hydroxide (Ca(OH)₂) followed by 6.3%of a 50% aqueous solution of 2-diethylaminoethylchloride hydrochloride(DEC). The reaction was run at 40° C. for 6 hrs. A 10% aqueoushydrochloric acid solution (HCl) was added to adjust the pH to 3.0. Themixture was filtered and the solids washed. A portion of the filter cakecontaining 50 g. of the cationic starch ether was dried and analyzed.Cationic N was 0.28%.

The remaining filter cake (about 200 g. starch) was reslurried in 150ml. water; 80 g. of sodium sulfate (Na₂ SO₄) were added; and the ph wasraised to about 11.0-11.5 by adding a 4.5% sodium hydroxide (NaOH)solution containing 10% Na₂ SO₄. A total of 19.0 g. (9.5%) of Reagent Awas added. The slurry was placed in a bath at 45° C. for 16 hrs. whilemaintaining the pH above 11.0 with the 4.5% NaOH solution. The pH wasadjusted to about 7.0-8.0 with 10% HCl. The resulting product wasfiltered, washed with water adjusted to pH 7.0-8.0, and dried. Itcontained 0.72% total N. The nitrogen content due to the acetalsubstituent was 0.44%.

(2) The DEC reaction was carried out as in (1) except that corn starchwas used. Cationic N was 0.29%. Acetal reaction was carried out using 5%potassium iodide (KI) as a catalyst (see U.S. Pat. No. 3,880,832 citedpreviously). A total of 1000 g. of the cationic corn starch wassuspended in 1250 ml. of water containing 300 g. Na₂ SO₄. An aqueoussolution of 40 g. NaOH, 50 g. Na₂ SO₄, and 710 g. water was added slowlyto the starch slurry. Then 300 g. of Reagent B were added all at oncefollowed by the KI. Reaction conditions were 16 hr. at 45° C. Thederivative was recovered as above but, after washing, it was resuspendedin water and 5 g. sodium bisulfite was added. The slurry was filteredbut not washed. The bisulfite salt prevents oxidation of the I⁻ salts toiodine which produces a brown color. Acetal N was 0.41%.

(3) The DEC reaction was carried out on a waxy maize starch using theprocedure of (1) except that 40% Na₂ SO₄ was used to repress swellingand 4.5% NaOH was used to maintain the pH at above 10.8. Cationic N was0.232%. The acetal reaction was carried out as in (1) except that 11%Reagent A (based on about 200 g. starch remaining in the slurry) wasused. No Na₂ SO₄ was added. The pH was adjusted to above 10.8 with 4.5%NaOH. Reaction conditions were 19 hr. at 40° C. Acetal N was 0.37%.

(4) The DEC and acetal reactions were carried out on a waxy maize starchusing Reagent A (9.5%) and the procedure of (3) except that 12% aqueouspotassium hydroxide was used to control the reaction and no Na₂ SO₄ wasused. Cationic and acetal N were 0.25% and 0.45% respectively.

(5) The DEC reaction was carried out on a waxy maize starch using theprocedure of (3). Cationic N was 0.26%. The acetal reaction was carriedout in 300 ml. of water containing 80 g. Na₂ SO₄. The pH was adjusted to11.2-11.5 using the NaOH/Na₂ SO₄ solution of (1). Reagent A (11%) wasused; the reaction conditions were 19 hr. at 30° C. Acetal N was 0.40%.

(6) The DEC and acetal reactions were carried out as in (5) except at50° C. Cationic and acetal N were 0.26% and 0.32%, respectively.

Part B. Simultaneous Reaction

(1) An unmodified waxy maize starch was slurried in water and 3.15% DECand 12% Reagent A were added while maintaining the pH above 11.0 with a4.5% NaOH solution. The reaction mixture was maintained at 45° C. and pH11.0-11.5 for 16 hr. and then neutralized to pH 7.5. The product wasrecovered as above. It had a total N content of 0.77%.

(2) A similar reaction was carried out using potato starch (200 g.) and16 parts of a 50% solution of 3-chloro-2-hydroxypropyl trimethylammonium chloride and 12% Reagent A. The product contained 0.91% totalN. Cationic N was not determined (theoretical was about 0.3% maximum).The potato starch base contained about 0.013% N. Acetal N should beabout 0.60%.

Part C. Consecutive Reaction Using Acetal Reagent Followed by CationicReagent

An unmodified waxy maize starch (1000 g.) was slurried in 1500 ml. watercontaining 400 g. Na₂ SO₄, and the pH was raised to 11.2 with a NaOHsolution made by dissolving 40 g. of solid NaOH and 90 g. Na₂ SO₄ in 770g. water. The above acetal reagent A (10%) was added and the reactionwas maintained at pH 11.2 and 45° C. for 16 hrs. The product (recoveredas above) had an acetal N content of 0.57%.

The resulting acetal (200 g.) was reacted with 16 g. of the 50% aqueousDEC solution as described above. The final product contained 0.72% totalN.

Part D. Dry Reaction

200 g. of a cationic, waxy maize starch (0.26% nitrogen) made as in PartA--No. 3 were impregnated in a Hobart mixer with a solution consistingof 24 g. acetal reagent A, 2.5 g. NaOH and 24 ml. water. After stirringto insure a homogeneous blend, the sample was placed in a jar in an ovenat 75° C. After 2 hrs. the sample was suspended in 95-100% ethanol andfiltered. The resulting filter cake was resuspended in a 1:1 (by volume)ethanol-water mixture, pH was adjusted to 7.5, and the sample wasfiltered and washed repeatedly with the 1:1 ethanol-water. FinalNitrogen on the purified product was 0.48%, and therefore an acetalNitrogen of 0.22% was obtained by the "dry" reaction.

EXAMPLE II

This example describes the preparation of additional starch acetalsusing reagents other than the acetamide reagents of the previousexample.

Acetal Reagent Preparation

Reagent D--N-(2,2-Dimethoxyethyl)-N-methyl-3-chloropropionamide, whichhas the formula ##STR38## was prepared according to the procedure usedto make Reagent A except that chloropropionyl chloride (32.7 g.) wassubstituted for chloroacetyl chloride. The product was isolated as apale yellow liquid.

Reagent E--N-(2,2-Dimethoxyethyl)-N-methyl acrylamide, which has theformula ##STR39## was prepared according to the procedure used to makeReagent A except that acryloyl chloride (23.3 g.) was used instead ofchloroacetyl chloride and 4-t-butylcatechol (0.1 g.) was added to theorganic phase before removal of the solvent. The final product wasisolated as a clear liquid by distillation (65°-66° C.-0.2-0.3 mm Hg.).

Reagent F--1,2-Epoxy-3,3-dimethoxypropane, which has the formula##STR40## was prepared from acrolein as described D. T. Weisblat et al.See J. Am. Chem. Soc., Vol. 75, p. 5893 (1953).

Reagent G--N-(2,2-Dimethoxyethyl)-N,N-dimethyl-N-(2,3-epoxypropyl)ammonium chloride, which has the formula ##STR41## was prepared byadjusting the pH of a 40% solution of dimethylaminoacetaldehyde diethylacetal (30.01 g) to pH 7.5 with concentrated HCl and then droppingepichlorohydrin (22.8 g.) into the solution. The reaction mixture washeld for 2 hrs. while maintaining the pH between 7.5-8.5 by the additionof concentrated HCl or 50% NaOH. The temperature was maintained at30-35° C. Impurities and excess reagent were removed from the reactionmixture by extraction with ethyl acetate (4 times with 65 ml. eachtime). The product was isolated as an aqueous solution which was pHadjusted to 7.0.

Starch Reactions

The starch reactions with Reagents D to G were carried out as in ExampleI, Part A, No. 1 using 30 g. Na₂ SO₄ in the slurry of starch (100 g.)and a solution of 3.4 g. NaOH and 5 g. Na₂ SO₄ in 70 g. water to adjustthe pH. The reagent amounts, starch base, and nitrogen content are shownbelow.

    ______________________________________                                                 % Cationic N           % Acetal N                                    Starch Base                                                                            in Base    Acetal Reagent                                                                            in Cationic Acetal                            ______________________________________                                        Waxy corn                                                                              0.270      15% D       0.240                                         Waxy corn                                                                              0.270      12% E       0.360                                         Waxy corn                                                                              0.270      12% F       None*                                         Corn     None       15% G       0.380                                         ______________________________________                                         *No nitrogen in acetal reagent                                           

EXAMPLE III

This example describes the preparation of cellulose acetals. They wereprepared using the general procedure of U.S. Pat. No. 4,129,722 (citedpreviously).

A total of 20 g. SPAN-80 (a surfactant available from Hercules) wasdissolved in 200 g. Isopar E (petroleum solvent composed mostly of C₈isoparaffins, b.p. of 116°-142° C.) in a 500 ml. flask equipped with athermometer, mechanical agitator, condenser and suitable size droppingfunnels. Cationic hydroxyethylcellulose (50 g.) grafted withdimethyldiallylammonium chloride (DMDAAC) was added to thesolvent-surfactant blend. Then 15 g. of Reagent A of Example I wasdissolved in 10 ml. water and added to the reaction mixture over a 30min. period. This was followed by addition of 8 ml. of 10 N NaOH. Thetemperature was raised to 50° C. and held 3 hrs., followed by cooling toroom temperature and neutralization to pH 8.0 with HCl. The cellulosederivative was filtered, washed with Isopar E and dried. Cationic N was0.81%. Total N after dialysis was 1.43%. Acetal N was therefore 0.62%.

Using an identical procedure methyl cellulose (Methocel from DowChemical Co.) and cellulose (C-8002 alpha-cellulose from Sigma Co.) werereacted with 30% and 40%, respectively, of Reagent A. Acetal N on themethyl cellulose was 0.54% before and after dialysis. Acetal N on thealpha-cellulose was 0.3% after exhaustive washing with water.

EXAMPLE IV

This example describes the preparation of the aldehydes.

The starch acetals were converted to the corresponding aldehydes byslurrying the acetal in water (e.g., 100 parts of water/1 part ofstarch) and adjusting the pH to 2.5-3.0 with a dilute solution ofhydrochloric acid. The starch acetals were cooked in a boiling waterbath, prior to, after, or during the acidification to gelatinize thestarch. The total cooking time was about 20 mins. The slurry was stirredduring the acid addition and/or initial cooking. The cook was cooledrapidly.

The cellulose acetals were converted to the corresponding aldehydes asabove but it was not necessary to cook the cellulose derivatives. Thegum acetals can be converted to the corresponding aldehydes in a likemanner.

EXAMPLE V

This example describes the use of the cationic starch aldehydes andcationic cellulose aldehyde as paper strength additives. The aldehydeswere added to the indicated paper furnish and handsheets were preparedat pH 6.0, dried at 121° C. (250° F.), cooled, cut into 1 in. strips,and cured at 105° C. (221° F.) for 5 min. The wet and dry tensilestrengths are reported as breaking length (B.L.). The addition level was20 lb./ton.

The derivatives and paper test results are given in Table I. All butNos. 20 and 21 imparted initial wet strength and dry strength and weresuperior to the prior art cationic dialdehyde starch in initial wetstrength. The cationic cellulose aldehyde provided the highest wet anddry strength.

EXAMPLE VI

This example shows the effect of pH on the aldehyde generation. It alsoillustrates the preparation of starch acetals containing mixed acetalsubstituent groups.

Part A--Preparation of The Mixed Acetal Reagents

Reagents H, I, and J were prepared by stirring 25 g. portions of ReagentA of Example I with 600 ml. of isopropanol (Reagent H), n-butanol(Reagent 1), and tert-butanol (Reagent J) with 5 drops of concentratedhydrochloric acid for about 18 hours at room temperature. The reactionmixtures were filtered and stripped on a rotary evaporator at

40°-50° C., followed by vacuum pumping at 0.5 mm. Hg for 2 hours at roomtemperature. NMR analysis showed that about 10-20% of the dimethoxygroups (i.e., --CH(OCH₃)₂) had been exchanged with the respectivesolvents thus introducing isopropoxy groups [i.e., --CH(OCH(CH₃)₂)₂ ],n-butoxy groups [i.e., --CH(OCH₂ CH₂ CH₂ CH₃)₂ ], (and tert-butoxygroups [ie., [--CH(OC(CH₃)₃)₂ ].

                                      TABLE I                                     __________________________________________________________________________                                          % Acetal N                                                                           Initial Wet                                                                         Dry                        Cationic Derivative                                                                             % Cationic                                                                          Acetal                                                                             Method of                                                                              in Cationic                                                                          Strength                                                                            Strength                   No.  Starch Base  N in Base                                                                           Reagent                                                                            Preparation                                                                            Acetal (B.L.-m.)                                                                           (B.L.-m.)                  __________________________________________________________________________    Blank                                                                              None           --  --   --       --      39   1682                       Control                                                                            Cationic Waxy Corn                                                                         0.293 None *        None    87   1866                        1   Corn Aldehyde                                                                              0.293 30% B                                                                              See Ex. I-Part A2                                                                      0.409  444   2392                        2   Waxy Corn Adlehyde                                                                         0.276 20% B                                                                              See Ex. I-Part A2                                                                      0.376  352   2358                        3   Corn Aldehyde                                                                              0.278 10% A                                                                              See Ex. I-Part A2                                                                      0.502  414   --                          4   Corn Aldehyde                                                                              0.278 12% A                                                                              See Ex. I-Part A2                                                                      0.347  729   3199                        5   Waxy Corn Aldehyde                                                                         0.270 12% C                                                                              See Ex. I-Part A1                                                                      0.240  521   3019                        6   Corn Aldehyde                                                                              0.276  6% B                                                                              See Ex. I-Part A2                                                                      0.670  413   3092                        7   Corn Aldehyde                                                                              0.260 30% B                                                                              See Ex. I-Part A1                                                                      0.347  526   2999                        8   Corn Aldehyde                                                                              0.287 10% A                                                                              See Ex. I-Part A2                                                                      0.491  448   2439                        9   Corn Aldehyde                                                                              0.287 30% A                                                                              See Ex. I-Part A2                                                                      0.833  403   2105                       10   Waxy Corn Aldehyde                                                                         0.240 20% B                                                                              See Ex. I-Part A2                                                                      0.202  406   2868                       11   Waxy Corn Aldehyde                                                                         0.237 10% A                                                                              See Ex. I-Part A2                                                                      0.494  552   2811                       12   High Amylose Corn                                                                          0.520 20% A                                                                              See Ex. I-Part A2                                                                      0.600  381   2165                            Aldehyde (70% Amylose)                                                   13   Fluidity Corn Aldehyde                                                                     0.260 20% B                                                                              See Ex. I-Part A1                                                                      0.520  526   2997                            (79 WF)                                                                  14   Fluidity Waxy Corn                                                                         0.240 12% A                                                                              See Ex. I-Part A1                                                                      0.456  542   3010                            Aldehyde (35 WF)                                                         15   Fluidity Waxy Corn                                                                         0.240 12% A                                                                              See Ex. I-Part A1                                                                      0.447  334   2203                            Aldehyde (85 WF)                                                         16   Waxy Corn Aldehyde**                                                                       N.D.  12% A                                                                              See Ex. I-Part 1B                                                                      N.D.   394   1907                       17   Waxy Corn Aldehyde                                                                         0.270 15% D                                                                              See Ex. II                                                                             0.240  474   2744                       18   Waxy Corn Aldehyde                                                                         0.270 12% E                                                                              See Ex. II                                                                             0.360  476   2504                       19   Waxy Corn Aldehyde                                                                         0.270 12% F                                                                              See Ex. II                                                                             None   317   2268                       20   Corn Aldehyde                                                                              None  12% G                                                                              See Ex. II                                                                             0.38    69   1372                       21   Waxy Corn Aldehyde                                                                         0.27  10% S                                                                              See Ex. XI                                                                             None    89   1483                       22   Waxy Corn Aldehyde                                                                         0.27  12% W                                                                              See Ex. XV                                                                             None   192   1518                       23   Waxy Corn Aldehyde                                                                         0.27  15% X                                                                              See Ex. XVI                                                                            N.D.   190   1603                       24   Waxy Corn Aldehyde                                                                         0.27  10% Y                                                                              See Ex. XVII                                                                           None   205   1594                       __________________________________________________________________________     *Prepared as in Part A1 of Example I except that no acetal reagent was        used.                                                                         **Total N was 0.773%.                                                         N.D.  Not determined.                                                    

Part B--Preparation of the Starch Derivatives

Cationic waxy maize acetal starch derivatives were prepared using theabove reagents and the procedure of Example I, Part A (3).

    ______________________________________                                        Starch   Reagent    % Cationic N                                                                             % Acetal N                                     ______________________________________                                        25       H          0.28       0.37                                           26       I          0.28       0 33                                           27       J          0.28       0.34                                           Control  --         0.28       --                                             ______________________________________                                    

Part C--Evaluation of Wet Strength after Conversion to Aldehyde atVarious pH Values

One gram samples of the above starch acetals were slurried in water to atotal weight of 100g. and the pH was adjusted to pH 2.5 or 5.0. Thestarches were cooked and evaluated in paper handsheets as in ExampleVIII, Part A. The results are shown in Table II.

                  TABLE II                                                        ______________________________________                                                                          Initial                                     Cationic              Addition Level                                                                            Wet Strength                                Starch Derivative No.                                                                      Cook pH  (lb./ton)   (B.L.-m.)                                   ______________________________________                                        25           2.5      10          279                                         25           2.5      20          409                                         25           5.0      10           82                                         25           5.0      20          287                                         26           2.5      10          231                                         26           2.5      20          370                                         26           5.0      10           91                                         26           5.0      20          279                                         27           2.5      10          251                                         27           2.5      20          413                                         27           5.0      10           97                                         27           5.0      20          294                                         Control      5.0      20           89                                         ______________________________________                                        (Cationic Starch Base)                                                        ______________________________________                                    

The results show that the wet strength was much higher for starch acetalderivatives cooked at pH 2.5 rather than pH 5.0. At the higher additionlevel the wet strength increased even for the derivatives cooked at thehigher pH. This shows aldehydes were generated at the higher pH.

EXAMPLE VII

This example describes the temporary wet strength provided by thecationic aldehydes. The aldehydes were evaluated for bothtissue/toweling applications (Part A) and board and bag applications(Part B).

Part A

The derivatives evaluated were the aldehydes prepared from a cationicwaxy corn starch acetal similar to the derivative of Example I--Part A-1and the cationic cellulose acetal Example III. One starch aldehyde wascooked as in Example IV, but at a pH of 7, to provide a liquid starchacetal. The acetal was then hydrolyzed to the aldehyde by adjusting thepH to 2.5 and then heating at 90°-100° C. for 10-15 min. It was thenadded to the paper furnish. The other starch aldehyde was prepared bycooking the acetal at pH 2.5.

One cationic cellulose acetal was cooked as above at pH 7 to provide aliquid cellulose acetal. It was then hydrolyzed to the aldehyde byadjusting the pH to 2.5 and cooked as above. The other cellulose acetalwas cooked at pH 2.5. For comparison, the cationic starch base, as wellas cationic starch acetal which had been cooked at a pH of 7 but nothydrolyzed, were evaluated (see Table II).

The addition level was 20 lb./ton. The furnish was a 50:50 bleachedsulfite:bleached Kraft. The paper sheets were prepared on the Noble andWood Sheet Mold. The paper weight was about 5 lb./1000 ft.² The wet anddry strength results are shown in Table III.

The results show that all the cationic derivatives improved the drystrength with the cationic starch aldehyde providing the mostimprovement. Only the cationic aldehydes improved the wet strength. Thestarch aldehyde prepared by simultaneously cooking and hydrolyzing theacetal was better than the precooked and subsequently hydrolyzed acetalto dry strength, initial wet strength, and temporary wet strength.

                                      TABLE III                                   __________________________________________________________________________                     Wet Strength                                                                            % Relative                                                    Dry   (B.L. in m.)                                                                            Wet Strength*                                                  Strength 30 16     30 16                                          Sample     (B.L. in m.)                                                                        Initial                                                                           Min.                                                                             Hr.                                                                              Initial                                                                           Min.                                                                             Hr.                                         __________________________________________________________________________    Blank      1210   49  20                                                                              33  4.1                                                                               1.7                                                                             2.7                                         Cationic Starch                                                                          1640   83  43                                                                              N.D.                                                                              5.1                                                                               2.6                                                                             2.1                                         Base                                                                          Cationic Starch                                                                          1530   71  51                                                                              32  4.7                                                                               3.3                                                                             2.1                                         Acetal                                                                        (comparative)                                                                 Cationic Starch                                                                          2140  382 260                                                                              122                                                                              17.9                                                                              12.1                                                                             5.7                                         Aldehyde (cooked                                                              at pH 2.5)                                                                    Cationic Starch                                                                          1830  296 217                                                                              N.D.                                                                             16.2                                                                              11.9                                                                             N.D                                         Aldehyde                                                                      (precooked acetal)                                                            Cationic   1550  335 258                                                                              N.D.                                                                             21.6                                                                              16.6                                                                             N.D                                         Cellulose                                                                     Aldehyde                                                                      Cationic Cellulose                                                                       1610  350 277                                                                              N.D.                                                                             21.7                                                                              17.2                                                                             N.D.                                        Aldehyde (precooked                                                           acetal)                                                                       __________________________________________________________________________     *Wet Strength/Dry Strength × 100.                                       N.D.  Not determined.                                                    

Part B

Some of the derivatives were also evaluated at 20./ton in a furnish of100% unbleached Kraft containing 3% alum (i.e., aluminum sulfate). Thepaper weight was about 42 lb./1000 sq. ft. The results are shown inTable IV.

The results again show that all the cationic derivatives improved thedry strength with the cellulose aldehydes being the best. Only thealdehydes provided wet strength.

                                      TABLE IV                                    __________________________________________________________________________                     Wet Strength                                                                            % Relative                                                    Dry   (B.L. in m.)                                                                            Wet Strength*                                                  Strength 30 16     30 16                                          Sample     (B.L. in m.)                                                                        Initial                                                                           Min.                                                                             Hr.                                                                              Initial                                                                           Min.                                                                             Hr.                                         __________________________________________________________________________    Blank      5330   516                                                                              455                                                                              360                                                                               9.7                                                                               8.5                                                                              6.8                                        Cationic Starch                                                                          6050   533                                                                              471                                                                              N.D.                                                                              8.8                                                                               7.8                                                                             N.D.                                        Base                                                                          Cationic Starch                                                                          5720   507                                                                              404                                                                              N.D.                                                                              8.9                                                                               7.1                                                                             N.D.                                        Acetal                                                                        Cationic Starch                                                                          5711  1100                                                                              746                                                                              637                                                                              19.3                                                                              13.1                                                                             11.2                                        Aldehyde (cooked                                                              at pH 2.5)                                                                    Cationic   6710  1660                                                                              1400                                                                             1160                                                                             24.7                                                                              20.9                                                                             17.3                                        Cellulose                                                                     Aldehyde                                                                      Cationic Cellulose                                                                       6160  1640                                                                              1420                                                                             N.D.                                                                             26.6                                                                              23.1                                                                             N.D.                                        Aldehyde (precooked                                                           acetal)                                                                       __________________________________________________________________________

EXAMPLE VIII

This example describes the preparation of the aldehyde-containing starchderivative having the structure Starch-O---CH₂ --CH═CH--CHO.

Part A--Preparation of The Acetal-Containing Reagent4-Chloro-1,1-dimethyoxy-2-butene (Reagent K) was prepared by reacting7.46 g. of 4-chloro-2-butenal with 200 ml. of anhydrous methanol and acatalytic amount of hydrochloric acid. The reaction mixture was stirredat room temperature for 16 hours, neutralized with sodium carbonate,filtered, and concentrated.

Part B--Preparation of The Acetal-Containing Starch Derivative

A total of 25 g. of corn starch was slurried in a solution of 0.6 g.sodium hydroxide and 7.5 g. sodium sulfate in 33 ml. of water, and 2.75g. of the above reagent (11% treatment) were added. The reaction wascarried out at 48° C. for 16 hours. The slurry was neutralized to pH 7.7with 3:1 hydrochloric acid, filtered, and washed with 400 ml. of water(pH 7.5-8) and then with 50 ml. of acetone. The resulting starch acetalwas air dried.

Part C--Preparation of The Aldehyde-Containing Starch Derivative

A total of 8 g. of the above starch acetal was sluried in 96 ml. ofwater adjusted to pH 2.5 with 3:1 HCl. It was then cooked with stirringfor 20 minutes in a boiling water bath to simultaneously convert theacetal to the aldehyde and cook the starch. Upon cooling, the cookcontaining the aldehyde formed a soft gel with a very heavy viscosityand very lumpy texture. Gel formation indicated the presence of thealdehyde groups. For comparison, the corn starch acetal was cooked asabove but without acidification. Upon cooling, the cook appeared to bestable with an opaque soft set and grainy texture. The presence of thealdehyde group was verified by the titration procedure previouslydescribed. It contained 0.2% more latent aldehyde than the base starch.

EXAMPLE IX

This example describes the preparation of the aldehyde-containing starchderivative having the structure Starch-O-CH₂ C.tbd.C-CHO.

Part A--Preparation of The Acetal-Containing Reagent

4-Bromo-1,1-diethoxy-2-butyne (Reagent L) was prepared according to theprocedure of R. Epsystein and S. Marszak, Bull. Soc. Chim. Fr., I, pp.313-17 (1968). A total of 74.1 g. (0.40 mole) of propargyl bromine,59.28 g. (0.40 mole) of triethylorthoformate, and 3.2 g. (0.010 mole) ofzinc iodide were combined in a reaction flask fitted with a packeddistillation column and a stillhead. The mixture was heated to 100°-110°C. and ethanol was removed by slow distillation over 2.5 hours. Hexane(96 ml.) was added as required to maintain the stillhead temperaturebelow 80° C. The pot residue was diluted with 200 ml. methylenechloride, washed with water and brine, dried with magnesium sulfate,filtered, and then distilled. A forerun of ethylorthoformate wascollected, followed by the acetal at 50°-77° C./5-10 mm.

Part B--Preparation of The Acetal-Containing Starch Derivative

A total of 25 g. of corn starch was slurried in a solution of 0.6 g.sodium hydroxide and 7.5 g. sodium sulfate in 33 ml. of water, and 2.86g. of the above reagent (11% treatment) were added. The reaction wascarried out at 45°-50° C. for 16 hours. The slurry was neutralized to pH7.6 with 3:1 hydrochloric acid, filtered, and washed with 300 ml. ofwater (pH 7.5-8) and then with 100 ml. of acetone. The resulting starchwas air dried.

Part C--Preparation of The Aldehyde-Containing Starch Derivative

The starch acetal was converted to the aldehyde using the acidificationand cooking procedure of Example VIII. The cook formed a gel while stillhot. The cooled gel was opaque and golden yellow. For comparison, thecorn starch acetal was cooked as above except without acidification.Upon cooling, the opaque cook appeared to be very stable with a verysoft set and smooth lumpy texture. Gel formation indicated the presenceof aldehyde groups.

EXAMPLE X

This example describes the preparation of starch derivatives containingaldehyde groups which have the structures ##STR42##

Part A--Preparation of The Acetal Reagents

A total of 125 g. (0.8 mole) of 1,4-dichloro-2-butene was heated to 50°C. and 12.9 g. (0.08 mole) of dimethylamino acetaldehyde diethyl acetalwas added dropwise over 1 hr. The reaction mixture was then heated to70° C. and stirred for 2 hours. Excess dichlorobutene was removed byvacuum distillation (74°-76° C./40 mm. Hg) to give an orange syrup. Thecrude product was dissolved in 200 ml. water and washed three times with40 ml. of methylene chloride. The aqueous solution was then concentratedto a viscous orange oil on a rotary evaporator (pot temperature 50° C.,pressure 3-10 mm.). The product (Reagent M),N,N-dimethyl-N-(2,2-diethoxy ethyl)-N-(4-chloro-2-butenyl) ammoniumchloride, contained 7.5% organic chlorine.

In a like manner, N,N-dimethyl-N-(2,2-dimethoxyethyl)-N-(4-chloro-2-butenyl) ammonium chloride (Reagent N) andN,N-bis-(2,2-diethoxy ethyl)-N-methyl-N-(4-chloro-2-butenyl) ammoniumchloride (Reagent 0) were prepared using dimethylamine acetaldehydedimethyl acetal and N,N-bis(2,2-diethoxy ethyl)methyl amine instead ofthe dimethylaminoacetaldehyde diethyl acetal.

Part B--Preparation of the Acetal-Containing Starch Derivative

The above reagents were reacted with corn starch using the proceduredescribed in Example IX. The starch products were analyzed for N. Thereactions were as follows:

    ______________________________________                                                                   Acetal N                                                                      in Cationic                                        Starch Base  Acetal Reagent (%)                                                                          Acetal (%)                                         ______________________________________                                        Waxy corn    M 12          0.456                                              Corn         N 10          0.444                                              Corn         0.11          0.230                                              ______________________________________                                    

Part C--Preparation of The Aldehyde-Containing Starch Derivative Theacetal-containing derivatives were converted to the correspondingaldehydes using the procedure of Part C of Example VIII. Upon cooking atlow pH there was an increase in viscosity indicating the presence ofaldehyde groups. Cooking without acidification gave stable solutionswhich did not retrograde into gels. EXAMPLE XI

The example describes the preparation of aldehyde-containing derivativeswhich have the structure ##STR43##

Part A--Preparation of The Acetal-Containing Reagents

A-i. The following alcohol-containing acetals were prepared and thenreacted with epichlorohydrin to introduce the epoxides groups necessaryfor the starch reaction.

Preparation of The Alcohol-Containing Acetals Reagent P2-[2-(2-Hydroxyethoxy)propyl]-1,3-dioxolane ##STR44##

A total of 35.0 g. (0.5 mole) of crotonaldehyde and 124 g. (2.0 mole ofethylene glycol were dissolved in 200 ml. of toluene and added to a 500ml. round bottom flask equipped with magnetic stir bar, heating mantle,Dean-Starke trap, reflux condenser and nitrogen inlet.p-Toluene-sulfonic acid (0.6 g.-0.003 mole) was added to the mixture.The mixture was refluxed until the calculated amount of water (9.0 g.)was collected, cooled quickly in an ice bath to room temperature, andthen dried and simultaneously neutralized with excess sodium carbonate.The solution was filtered and the solvent removed under vacuum(rotovap). The residual brown oil was subjected to high vacuumdistillation The first fraction, collected between 55 and 80° C. at 0.5mm./Hg, was primarily ethylene glycol. The second fraction, collected atbetween 80° and 90° C., was primarily the above dioxolane with a traceamount of ethylene glycol which can be removed by column chromatography(neutral alumina: ether/petroleum ether: 1/1). Yield was 50-60%.##STR45##

This dioxolane was prepared from acrolein using the above conditions. Ithad a boiling point of 75-85° C. at 0.5 mm./Hg. Yield was 50-60%.Reagent R 3-Hydroxy-2,2-dimethylpropionaldehyde Dimethyl Acetal##STR46##

A total of 50.0 g. (0.49 mole) of 3-hydroxy-2,2-dimethylpropionaldehydewas dissolved in 500 ml. of anhydrous methanol and placed in a 1000 ml.round bottom flask equipped with magnetic stir bar and drying tube. Onedrop of concentrated hydrochloric acid was added and the solution wasallowed to stir overnight. The reaction mixture was then neutralizedwith sodium carbonate, filtered, and the solvent removed under vacuum.The resulting opaque white oil was vacuum distilled to give a waterclear oil having a boiling point of 155° C. at house vacuum. Yield was55%.

Modification of The Alcohol-Containing Acetals with EpichlorohydrinProcedure 1

This procedure was used with the water-soluble, alcohol-containingacetals.

A total of 6.0 g. of appropriate dimethyl acetal (0.035 mole) was addedto 1.54 g. sodium hydroxide (0.038 mole) in a 100 ml. round bottom flaskequipped with magnetic stir bar, reflux condenser, and nitrogen inlet.After stirring for 30 mins., 3.89 g. (0.042 mole) of epichlorohydrin in50 ml. of methyl ethyl ketone was added quickly, and the reactionmixture was allowed to reflux overnight under a nitrogen atmosphere. Theresulting oil was mixed with 250 ml. of toluene, and the toluene wasthen distilled off at atmospheric pressure to remove any residualepichlorohydrin. The sample was freed of toluene by subjecting it tohigh vacuum overnight. Yield was 60-85%.

In a like manner Reagents P and Q were reacted with epichlorohydrin.

Procedure 2

This procedure was used with the water-insoluble, alcohol-containingacetals.

A total of 2.67 g. of a 60% oil dispersion of sodium hydride (0.0676mole) was added to a 100 ml. three neck round bottom flask equipped withreflux condenser, addition funnel, magnetic stir bar, and nitrogeninlet. The oil was removed by triturating three times with 25 ml. ofpetroleum ether. Then 10.0 g. 3-hydroxy-2,2-dimethylpropionaldehydedimethyl acetal (0.0676 mole) [Reagent R] was dissolved in 20 ml. oftetrahydrofuran (THF) and added to the mixture dropwise over 30 mins.The reaction mixture was allowed to stir for 30 mins. before 6.9 g.(0.0743 mole) epichlorohydrin was added. The reaction was refluxedovernight, cooled, and checked for active hydride by adding a drop ofmethanol. If bubbling was detected, methanol was added dropwise untilall bubbling stopped. The reaction mixture was filtered and the solventwas removed under vacuum. The product was freed of residualepichlorohydrin by azeotropic distillation using tolene (200 ml.).

A-II. The following alcohol-containing aldehyde was first reacted withepichlorohydrin to introduce the epoxide functionality and the aldehydewas then converted to the acetal.

Part B Preparation of The Acetal-Containing Starch Derivatives

The following procedure was used to prepare the starch derivatives. Asolution of 9.0 g sodium sulfate (36% based on starch) was dissolved in40 ml. of distilled water and 0.375 g. sodium hydroxide (1.5% based onstarch) was dissolved in the salt solution. A total of 25 g. of starchwas added quickly and shaken to a uniform consistency. The indicatedreagent was added and the container was sealed and placed in a tumblerand heated at 45° C. for 30 hours. The starch slurry was cooled to roomtemperature and neutralized to pH 7.5 with HCl. The starch was thenfiltered, washed three times with 100 ml. of water and twice with 100ml. isopropanol, and air dried. It was analyzed by titration.

The starch reactions are summarized below:

    ______________________________________                                                                   Reaction                                           Starch  Acetal     NaOH    Time   CHO by                                      Base*   Reagent (%)                                                                              (%)     (hr.)  Titration (%)                               ______________________________________                                        corn    P 10       1.50    18     0.40                                        "       P 10       3.00    18     0.74                                        "       Q 10       1.75    18     N.D.-Strong gel                             "       R 10       1.50    18     0.31                                        "       R 10       3.00    18     0.10                                        ______________________________________                                         N.D.  not determined                                                          *Waxy maize starch was treated with 3% DEC prior to the acetal reagent        reaction and contained 0.27% N.                                          

Part C Preparation of The Aldehyde-Containing Starch Derivatives

The starch acetals were converted to the aldehydes using the procedureof Example IV.

EXAMPLE XIV

This example describes the preparation of aldehyde-containingderivatives which have the structure ##STR47##

Part A--Preparation of The Cyclic Acetal-Containing Reagents

Reagent U 2-[2-(3-Chloro-2-hydroxypropyl)ethyl]-5,5-dimethyl-1,3-dioxane 2-Ethenyl-5,5-dimethyl-1,3-dioxane was prepared by adding 15.4g. of acrolein (9.275 mole) and 26.0 g. (0.25 mole)2,2-dimethyl-1,3-propanediol to a 100 ml. round bottom flask equippedwith magnetic stir bar and thermocouple. Hydrochloric acid (0.1 ml. 37%)was added to the reaction and the temperature dropped to about 5° C.After all of the diol was dissolved, the reaction exothermed toapproximately 45° C. After the reaction was cooled to 30° C., themixture was placed in a separatory funnel. The lower aqueous layer wasremoved and the organic layer simultaneously neutralized and dried withexcess sodium carbonate (anhydrous). The material was filtered anddistilled (Bp 40° C. at 10 mm/Hg) to give a water clear liquid.

A total of 14.2 g. (0.1 mole) of the above dioxane, 11.6 g. (0.105 mole)of 3-chloro-1,2-propanediol, and 0.03 g. of p-toluenesulfonic acid(0.00015 mole) were introduced into a 250 ml. round bottom flaskequipped with magnetic stir bar, heating mantle, reflux condenser, anddrying tube. Cyclohexane (100 ml.) was added to the flask and thereaction was allowed to reflux overnight. The reaction was then cooledto room temperature, neutralized with sodium carbonate, washed threetimes with 50 ml. of water, dried over sodium carbonate, filtered, andthe solvent removed under vacuum. The resulting water clear oil requiredno further purification.

Reagent V2-[2-(3-Chloro-2-hydroxypropyl)propyl]-5,5-dimethyl-1,3-dioxane

2-Propenyl-5,5-dimethyl-1,3-dioxane was prepared as above except thatcrotonaldehyde was used in place of the acrolein. Due to the fact thatcrotonaldehyde does not exotherm, as does acrolein, the reaction was runin a water bath at 35°-45° C. and then cooled to room temperature toseparate the water. The product had a boiling point of 55° C. at 5 mm.Hg. The resulting dioxane was then reacted with 3-chloro-1,2-propanediolas described above.

Part B--Preparation of The Acetal-Containing Starch Derivative

A solution of 20 g. of sodium sulfate in 65 ml. of water was prepared inan eight ounce tall bottle, in which sodium hydroxide (2.0 g) wasdissolved. A total of 50 g. of the indicated starch was added quickly tothe solution and stirred by means of an overhead stirrer. The indicatedreagent was added to the slurry and the bottle was sealed and placed ina tumbler overnight at 45° C. In the morning the slurry was cooled toroom temperature and neutralized to pH 8 with 3:1 HCl. The slurry wasthen filtered and the resulting cake was washed twice with 300 ml. ofwater and twice with 300 ml. of isopropanol. The cake was then crushedby hand and air-dried to approximately 12% moisture.

The starch reactions are summarized below.

    ______________________________________                                        Starch   Acetal     NaOH    Reaction                                                                              CHO by                                    Base*    Reagent (%)                                                                              (%)     Time (hr.)                                                                            Titration (%)                             ______________________________________                                        corn     U 10       1.5     18      0.304                                     waxy maize                                                                             U 10       3.0     18      0.637                                     "        U 10       3.0     18      N.D.                                      "        U 10       2.5     18      N.D.                                      "        U 10       2.0     18      N.D.                                      "        V 10        2.25   24      0.42                                      ______________________________________                                         N.D.  not determined                                                          *The waxy maize starch was treated with 3% DEC and contained 0.27% N.    

Part C--Preparation of The Aldehyde-Containing Starch Derivative

The starch acetals were converted to aldehydes using the procedure ofExample IV.

EXAMPLE XV

This example describes the preparation of the derivative having thestructure ##STR48##

Part A--Preparation of The Acetal-Containing Reagent

Furfuryl glycidyl ether was prepared by adding 49 g. 2-furfuralcohol(0.50 mole) dissolved in 200 ml. of water to a water-alcohol solution of21.0 g. (0.525 mole) sodium hydroxide. It was stirred until the mixturereached ambient temperature. Then 51.4 g. (0.55 mole) of epichlorohydrinwere added. The temperature rose for two hours reaching a maximum at 30°C. The reaction was allowed to stir overnight. The product was extractedinto ether and dried over magnesium sulfate. The solvent was removedunder vacuum to give 54 g. of a light golden oil.

The ring opening reaction was carried out by introducing 42.5 g. (0.163mole) of the above ether dissolved in 250 ml. anhydrous methanol to a500 ml. three neck round bottom flask equipped with an addition funnel,magnetic stir bar, gas inlet, and cooling bath. The mixture was cooledto -45° C. A solution of 26.0 g. (0.325 mole) bromine in 65 ml. methanolwas added dropwise while maintaining the temperature at or below -35° C.After the addition was complete, the reaction mixture was placed in abath at -10° C. and stirred for two hours. The reaction mixture wascooled to -45° C. and neutralized by passing a stream of anhydrousammonia over the liquid until the mixture was at pH 8. The precipitate(ammonium bromide) was filtered and the filter cake was washed withether. Potassium carbonate (0.6 g-0.004 mole) was dissolved in theliquid and the solvent removed under vacuum. Ethyl acetate (100 ml.) wasadded and the resulting slurry was treated with activated charcoal andmagnesium sulfate. The solution was then filtered and the solventremoved under vacuum.

Part B--Preparation of The Acetal-Containing Starch Derivative

A total of 15-20 g. of sodium sulfate and 1-1.5 g. sodium hydroxide wasdissolved in 75 ml. of water and 50 g. of a starch was added. The aboveepoxide-containing acetal, Reagent W, (in the indicated amount based onstarch) was added with stirring. The container was placed in a tumblerat 45° C. for 24 hours. The reaction mixture was then cooled to roomtemperature and neutralized to pH 7.5, filtered, washed with water andalcohol, if necessary, and air dried overnight. The starch reactions aresummarized below.

    ______________________________________                                        Starch   Acetal     NaOH    Reaction                                                                              Aldehyde by                               Base*    Reagent (%)                                                                              (%)     Time (hr.)                                                                            Titration (%)                             ______________________________________                                        waxy maize                                                                             W 12       2.0     24      0.54                                      waxy maize                                                                             W 12       2.0     24      0.182                                     ______________________________________                                         *Treated with 3% DEC and containing 0.27% N.                             

Part C--Preparation of The Aldehyde-Containing Starch Derivatives

The starch acetals were converted to aldehydes using the procedure ofExample IV.

EXAMPLE XVI

This example describes the preparation of the derivative having thestructure ##STR49##

Part A--Preparation of The Acetal-Containing Reagent

N-Furfurylchloroacetamide was prepared by adding 20.0 g. (0.206 mole)furfuryl amine in sufficient toluene to make a 15% solution to a 500 ml.three neck round bottom flask equipped with magnetic stir bar, additionfunnel, and cooling bath and then adding 36 ml. of 20% sodium hydroxide.The mixture was cooled to 0°-5° C. and chloroacetyl chloride was addeddropwise so that the reaction temperature was maintained at 5°-10° C.After the addition, a solid deposited on the walls of the flask. It wasrecrystallized from ether as a light tan solid. Yield was 85%.

The ring was opened using the procedure described in Example XV to giveReagent X.

Part B--Preparation of The Acetal-Containing Starch Derivative

Using the procedure of Example XV the following starch reaction wascarried out.

    ______________________________________                                        Starch   Acetal     NaOH    Reaction                                                                              CHO by                                    Base*    Reagent (%)                                                                              (%)     Time (hr.)                                                                            Titration (%)                             ______________________________________                                        Waxy maize                                                                             X 15       3.0     18      0.59                                      ______________________________________                                         *Treated with 3% DEC and containing 0.27% N.                             

Part C--Preparation of The Aldehyde-Containing Starch Derivative

The starch acetals were converted to aldehydes using the procedure ofExample IV.

EXAMPLE XVII

This example describes the preparation of the derivative having thestructure. ##STR50##

Part A--Preparation of The Acetal-Containing Reagent

3-Chloromethyl furan was prepared by adding 5.0 g. (0.051 mole)3-furanmethanol and 6.8 g. (0.056 mole) collidine to a 250 ml. threeneck flask equipped with an addition funnel, nitrogen inlet and,magnetic stirrer. The mixture was cooled to 0° C. Lithium chloridedissolved in a minimum amount of dimethyl formamide was added dropwiseto the mixture while maintaining the temperature at about 5° C. Themixture was allowed to stir for an additional 1.5 hrs. and then pouredonto ice. The solution was extracted three times with 200 ml. of a 1:1mixture of ether/petroleum ether. The combined extracts were washed withsaturated copper nitrate until the blue color persisted. The extractswere dried over sodium sulfate and the solvent was removed under vacuumto give a light yellow liquid.

Treatment of the resulting product with bromine and methanol yieldedallylic diacetal, Reagent Y.

Part B--Preparation of The Acetal-Containing Starch Derivatives

Using the procedure of Example XV the following starch reactions werecarried out.

    ______________________________________                                        Starch   Acetal     NaOH    Reaction                                                                              Aldehyde by                               Base*    Reagent (%)                                                                              (%)     Time (hr.)                                                                            Titration (%)                             ______________________________________                                        waxy maize                                                                             Y 10       2.5     24      0.22                                      waxy maize                                                                             Y  5       2.5     24      0.20                                      waxy maize                                                                             Y 15       2.5     24      0.26                                      ______________________________________                                         *Treated with 3% DEC and containing 0.27% N.                             

Part C--Preparation of The Aldehyde-Containing Starch Derivatives

The starch acetals were converted to aldehydes using the procedure ofExample IV.

Now that the preferred embodiments of the invention have been describedin detail, various modifications and improvements thereon will becomereadily apparent to those skilled in the art. Accordingly, the spiritand scope of the present invention are to be limited only by theappended claims and not by the foregoing specification.

What is claimed is:
 1. An acetal selected from the group consisting ofacetals having the structure ##STR51## wherein R¹¹ and R¹² areindependently an alkyl, aryl, aralkyl, or alkaryl group when n is 1, R¹¹or R¹² is one of the groups when n is 2, or R¹¹ and R¹² are not presentwhen n is 3; wherein R¹³ is an alkyl group, which can contain an etherlinkage, or an aralkyl group; R¹⁶, R¹⁷, and R¹⁸ are individually analkyl group; A and A' are independently a lower alkyl group; A" and A"'are independently a lower alkyl group; X is a halogen anion; and Z is ahalogen or an epoxide group.
 2. The acetal of claim 1, wherein R¹¹ andR¹² are --CH₃ groups.
 3. The acetal of claim 1, wherein R¹³ is ##STR52##4. The acetal of claim 1, wherein R¹⁶ is --CH₂ --.
 5. The acetal ofclaim 1, wherein R¹⁷ is --CH₂ --.
 6. The acetal of claim 1, wherein R¹⁸is --CH₂ --.
 7. The acetal of claim 1 having the structure ##STR53##prepared by reacting a dialkylaminoacetaldehyde dialkyl acetal with a1,4-dihalo-2-butene.
 8. The acetal claim 7, wherein thedialkylaminoacetaldehyde dialkyl acetal is dimethylaminoacetaldehydediethyl acetal and the 1,4-dihalo-2-butene is 1,4-dichloro-2-butene;wherein the dialkylaminoacetaldehyde dialkyl acetal isdimethylaminoacetaldehyde dimethyl acetal and the 1,4-dihalo-2-butene is1,4-dichloro-2-butene; wherein the dialkylaminoacetadlehyde dialkylacetal is N,N-bis(2,2-diethoxyethyl) methyl amine and the1,4-dihalo-2-butene is 1,4-dichloro-2-butene.
 9. The acetal of claim 1having the structure ##STR54## wherein Z is the epoxide, which isprepared by the steps of (a) reacting crotonaldehyde and an alkyleneglycol to form a 2-[2-(2-hydroxyalkoxy)-propyl]-1,3-cyclic acetal and(b) reacting the 2-[2-(2-hydroxyalkoxy)propyl]-1,3-cyclic acetal with anepiahalohydrin.
 10. The acetal claim 9, where the alkylene glycol isethylene glycol, the epihalohydrin is epichlorohydrin, and the2-[2-(2-hydroxyalkoxy)propyl]-1,3-cyclic acetal is2-[2-(2-hydroxyethoxy)propyl]-1,3-dioxolane or wherein the alkyleneglycol is ethylene glycol, the epihalohydrin is epichlorohydrin, and the2-[2-(2-hydroxyalkoxy)ehtyl]-1,3-cyclic acetal is2-[2-(2-hydroxyethoxy)ethyl]-1,3-dioxolane.
 11. The acetal of claim 1having the structure ##STR55## wherein Z is the epoxide group, which isprepared by the steps of (a) reacting 2-furfuralcohol and anepihalohydrin to form a furfuryl glycidyl ether and (b) opening the ringof the furfuryl glycidyl ether by treatment with a halogen in analcohol.
 12. The acetal of claim 11, wherein the epihalohydrin isepichlorohydrin, the halogen is bromine, and the alcohol is methanol.13. The acetal of claim 1 having the structure ##STR56## where Z is thehalogen, which is prepared by the steps of (a) reacting furfuryl aminewith an haloacetyl chloride to form N-furfuryhalo- acetamide and (b)opening the ring of the N-furfurylhalo- acetamide by treatment with ahalogen in an alcohol.
 14. The acetal of claim 13, wherein thehaloacetyl chloride is chloroacetyl chloride, theN-furfurylhaloacetamide is N-furfurylchloroacetamide, the halogen isbromine, and the alcohol is methanol.
 15. The acetal of claim 1 havingthe structure ##STR57## wherein Z is the halogen, which is prepared bythe steps of (a) reacting 3-furanmethanol and collidine to form a3-halomethylfuran and (b) reacting the 3-halomethylfuran with a halogenand an alcohol.
 16. The acetal of claim 15 wherein the 3-halomethylfuranis 3-chloromethylfuran.
 17. The acetal of claim 1, wherein R¹¹ and R¹²are --CH₃ groups; R¹³ is ##STR58## and R¹⁸ are --CH₂ --.